In Southern Colorado, Southern Utah, Northern Arizona and Northern New Mexico have what's known as monsoon season from June through September.
Almost every day, usually in the afternoon, thunderstorms pop-up with rain and lightning for an hour or so, then dissipate.
It wouldn't surprise me if they got caught in one.
I lived in Pinetop, AZ at 7,500 ft (White Mountains) from Oct 1975 to early summer ‘76. I remember those almost-instantaneous summer storms well. I didn’t know about them when I moved there. It really was spectacular. Every afternoon around 3 pm, FLASH BOOM for 30 minutes, deluges and then it would blow over. It was amazing.